RESUMEN
OBJECTIVE: Tamoxifen is the most used agent to treat estrogen receptor-positive (ER+) breast cancer (BC). While it decreases the risk of cancer recurrence by 50%, many patients develop resistance to this treatment, culminating in highly aggressive disease. Tamoxifen resistance comes from the repression of ER transcriptional activity that switches the cancer cells to proliferation via nonhormonal signaling pathways. Here, we evaluate a potential strategy to overcome tamoxifen resistance by focused ultrasound (FUS), a noninvasive approach for the mechanical excitation of cancer cells. METHODS: Resistant and nonresistant ER+ BC cells and xenografts from patients with ER+ BC were treated with tamoxifen, FUS or their combination. The apoptosis, proliferation rate, gene expression and activity of estrogen receptor, and morphological changes were measured in treated cells and tissues. RESULTS: FUS caused the mechanical disruption of tamoxifen-resistant BC cells that in turn led to the upregulation of ERα-encoding gene expression and long-term re-sensitization of the cells to tamoxifen. Patient-derived xenografts treated with Tamoxifen and FUS demonstrated a significant reduction in tumor viability and proliferation and a strong structural damage to tumor cells and extracellular matrix. CONCLUSION: FUS can improve ER+ BC treatment by re-sensitizing the cancer cells to tamoxifen.
RESUMEN
Despite the initial success in treatment of localized prostate cancer (PCa) using surgery, radiation or hormonal therapy, recurrence of aggressive tumors dictates morbidity and mortality. Focused ultrasound (FUS) is being tested as a targeted, noninvasive approach to eliminate the localized PCa foci, and strategies to enhance the anticancer potential of FUS have a high translational value. Since aggressive cancer cells utilize oxidative stress (Ox-stress) and endoplasmic reticulum stress (ER-stress) pathways for their survival and recurrence, we hypothesized that pre-treatment with drugs that disrupt stress-signaling pathways in tumor cells may increase FUS efficacy. Using four different PCa cell lines, i.e., LNCaP, C4-2B, 22Rv1 and DU145, we tested the in vitro effects of FUS, alone and in combination with two clinically tested drugs that increase Ox-stress (i.e., CDDO-me) or ER-stress (i.e., nelfinavir). As compared to standalone FUS, significant (p < 0.05) suppressions in both survival and recurrence of PCa cells were observed following pre-sensitization with low-dose CDDO-me (100 nM) and/or nelfinavir (2 µM). In drug pre-sensitized cells, significant anticancer effects were evident at a FUS intensity of as low as 0.7 kW/cm2. This combined mechanochemical disruption (MCD) approach decreased cell proliferation, migration and clonogenic ability and increased apoptosis/necrosis and reactive oxygen species (ROS) production. Furthermore, although activated in cells that survived standalone FUS, pre-sensitization with CDDO-me and/or nelfinavir suppressed both total and activated (phosphorylated) NF-κB and Akt protein levels. Thus, a combined MCD therapy may be a safe and effective approach towards the targeted elimination of aggressive PCa cells.
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Hepatocellular carcinoma (HCC) is a highly fatal disease recognized as a growing global health crisis worldwide. Currently, no curative treatment is available for early-to-intermediate stage HCC, characterized by large and/or multifocal tumors. If left untreated, HCC rapidly progresses to a lethal stage due to favorable conditions for metastatic spread. Mechanochemical disruption of cellular structures can potentially induce phenotypic alterations in surviving tumor cells that prevent HCC progression. In this paper, HCC response to mechanical vibration via high-intensity focused ultrasound and a chemical disruptive agent (ethanol) was examined in vitro and in vivo. Our analysis revealed that mechanochemical disruption caused a significant overproduction of reactive oxygen species (ROS) in multiple HCC cell lines (HepG2, PLC/PRF/5, and Hep3B). This led to a decrease in cell viability and long-term proliferation due to increased expression and activity of death receptors TNFR1 and Fas. The cells that survived mechanochemical disruption had a reduced expression of cancer stem cell markers (CD133, CD90, CD49f) and a diminished colony-forming ability. Mechanochemical disruption also impeded HCC migration and their adhesion to vascular endothelium, two critical processes in hematogenous metastasis. The HCC transformation to a non-tumorigenic phenotype post mechanochemical disruption was confirmed by a lack of tumor spheroid formation in vitro and complete tumor regression in vivo. These results show that mechanochemical disruption inhibits uncontrolled proliferation and reduces tumorigenicity and aggressiveness of HCC cells through ROS overproduction and associated activation of TNF- and Fas-mediated cell death signaling. Our study identifies a novel curative therapeutic approach that can prevent the development of aggressive HCC phenotypes.
Asunto(s)
Carcinoma Hepatocelular/metabolismo , Neoplasias Hepáticas/metabolismo , Antígeno AC133/metabolismo , Animales , Apoptosis/genética , Apoptosis/fisiología , Carcinoma Hepatocelular/patología , Línea Celular Tumoral , Proliferación Celular/genética , Proliferación Celular/fisiología , Supervivencia Celular/fisiología , Femenino , Células Hep G2 , Células Endoteliales de la Vena Umbilical Humana , Humanos , Integrina alfa6/metabolismo , Neoplasias Hepáticas/patología , Masculino , Ratones , Células Madre Neoplásicas/metabolismo , Especies Reactivas de Oxígeno/metabolismo , Receptores Tipo I de Factores de Necrosis Tumoral/metabolismo , Antígenos Thy-1/metabolismo , Receptor fas/metabolismoRESUMEN
Chemical-based medicine that targets specific oncogenes or proteins often leads to cancer recurrence due to tumor heterogeneity and development of chemoresistance. This challenge can be overcome by mechanochemical disruption of cancer cells via focused ultrasound (FUS) and sensitizing chemical agents such as ethanol. We demonstrate that this disruptive therapy decreases the viability, proliferation rate, tumorigenicity, endothelial adhesion, and migratory ability of prostate cancer cells in vitro. It sensitized the cells to TNFR1-- and Fas--mediated apoptosis and reduced the expression of metastatic markers CD44 and CD29. Using a prostate cancer xenograft model, we observed that the mechanochemical disruption led to complete tumor regression in vivo. This switch to a nonaggressive cell phenotype was caused by ROS and Hsp70 overproduction and subsequent impairment of NFκB signaling. FUS induces mechanical perturbations of diverse cancer cell populations, and its combination with agents that amplify and guide remedial cellular responses can stop lethal cancer progression. IMPLICATIONS: Mechanochemical disruption therapy in which FUS is combined with ethanol can be curative for locally aggressive and castration-resistant prostate cancer.